A Two-Level Function Evaluation Management Model for Multi-Population Methods in Dynamic Environments: Hierarchical Learning Automata Approach

ABSTRACT

The fitness evaluation (FE) management has been successfully applied to improve the performance of multi-population methods for dynamic optimisation problems (DOPs). In this work, we extend one of its variants to address DOPs which was recently proposed by the authors. The aim of our proposal is to increase the efficiency of the FE management. To this end, we propose a technique based on hierarchical learning automata that manages FEs at two level: at first level the algorithm decides which population should be executed, and at the second level it specifies the operation that should be performed by the selected population. A detailed experimental analysis shows the effectiveness of our proposal.     

Human-Machine Collaboration in Robotics: Integrating Virtual Tools with a Collision Avoidance Concept using Conglomerates of Spheres

This paper describes how virtual tools that represent real robot end-effectors are used in conjunction with a generalized conglomerate-of-spheres approach to collision avoidance in such a way that telerobotic trajectory planning can be accomplished using simple gesture phrases such as put that there while avoiding that. In this concept, an operator (or set of collaborators) need not train for cumbersome telemanipulation on several multiple-link robots, nor do robots need a priori knowledge of operator intent and exhaustive algorithms for evaluating every aspect of a detailed environment model. The human does what humans do best during task specification, while the robot does what machines do best during trajectory planning and execution.Four telerobotic stages were implemented to demonstrate this strategic supervision concept that will facilitate collaborative control between humans and machines. In the first stage, virtual reality tools are selected from a toolbox by the operator(s) and then these virtual tools are computationally interwoven into the live video scene with depth correlation. Each virtual tool is a graphic representation of a robot end-effector (gripper, cutter, or other robot tool) that carries tool-use attributes on how to perform a task. An operator uses an instrumented glove to virtually retrieve the disembodied tool, in the shared scene, and place it near objects and obstacles while giving key-point gesture directives, such as cut there while avoiding that. Collaborators on a network may alter the plan by changing tools or tool positioning to achieve preferred results from their own perspectives. When parties agree, from wherever they reside geographically, the robot(s) create and execute appropriate trajectories suitable to their own particular links and joints. Stage two generates standard joint-interpolated trajectories, and later creates potential field trajectories if necessary. Stage three tests for collisions with obstacles identified by the operator and modeled as conglomerates of spheres. Stage four involves automatic grasping (or cutting etc.) once the robot camera acquires a close-up view of the object during approach. In this paper particular emphasis is placed on the conglomerate-of-spheres approach to collision detection as integrated with the virtual tools concept for a Puma 560 robot by the Virtual Tools and Robotics Group in the Computer Integrated Manufacturing Laboratory at The Pennsylvania State University (Penn State).     

Improving VDT workplaces in offices by use of a physiologically optimized screen with black symbols on a light background: basic considerations

Due to the increased importance and usage of self-managed virtual teams, many recent studies have examined factors that affect their success. One such factor that merits examination is the configuration or composition of virtual teams. This article tackles this point by (1) empirically testing trait-configuration effects on virtual team performance, which are based on supplementary, complementary and interaction person-team fit perspectives and (2) extending the suggested trait-configuration model to include virtual team configuration in terms of the perceived problem-solving demands of the task as a predictor of team performance. To this end, median regression techniques were applied to data from 62 self-managed virtual teams that used an asynchronous bulletin board for working on a case study analysis. The findings suggest a plausible negative main effect of within-team conscientiousness heterogeneity on team performance, operationalised as standardised team grade. This effect depends on the level of the within-team extroversion heterogeneity which helps to mitigate the negative effect of within-team conscientiousness heterogeneity on team performance. Furthermore, within-team heterogeneity of the perceived problem-solving demands of the task reduces team performance. Overall, this study proves that virtual team configuration matters, and demonstrates that the joint utilisation of multiple person-team fit perspectives for improving virtual team performance has merit. Implications for research and practice are further discussed.     

Another look at ‘being there’ experiences in digital media: Exploring connections of telepresence with mental imagery

Substantial multidisciplinary research has established foundational support for the consumer behaviour phenomenon that underlies the experience of telepresence within online social networks and other digital media products that provide hedonistic value. A review of major perspectives in this field provides justification of the important role mental imagery processes play in the phenomenon of telepresence. In line with this, we propose to extend existing approaches to mental imagery to reach the context of user experiences in digital media, and to theoretically connect telepresence with mental imagery. On this basis, and in conjunction with investigations bringing to light processes that intervene in the terrain of mental imagery, we present an integrative conceptual framework concerned with telepresence, and discuss the role of telepresence within a user’s hedonistic usage of digital media products.